Most applications contain two kinds of data:
- Transaction data. These desrcibe events that took place on a certain moment, for example orders, deliveries, payments,
- SItuation data. These describe situations that exist for some time.
Usually transaction data contain a date so that they can be considered historical. Situation data are usually only included with respect to the present. Outdated data is replaced or deleted. Of couse this simplfies the applications substantially, but at the price of losing historical data*.
Historical situation data can also describe situations in the past. They are not replaced or deleted if the situations they describe have changed. They can be used to justify decesions later on when the situation they where based on has changed. Furthermore trends, causes and effects can be tracked down ad investigated.
Last decade application development tecniques like frameworks have brought database applications within the reach of small businesses and research projects. But with there focus on 'CRUD' these techniques share the basic simplification only to describe current situations. If historical situation data are treated in isolation this does not pose a problem, but if relations between historical data are included the usual techniques come short.
The Historical Data Mangement extension is designed to lift these limitations. This allows application developers to develop functionality with historical situation data in the same modern way as with ordinary data. The extension offers:
- relations between historical situation data that take temporal validity into account
- calculations with historical numbers whose temporal validity does not have to be synchronized. This results in multiple results each valid for a period of their own,
- searching and sorting over relationships within the validity of the data searched for and sorted
- time travel function to slice out the data valid on a certain date or within a certain period
- mutation of historical data with validation of historical consistency. This allows one to correct errorneous data safely and to enter historical data in non-histrorical order.
This extension has been used sucessfully to develop a historical data management application. If you have application requirements that need hirtorical data or if you are doing longitudinal or historic research and require a database application, please contact MetaClass for more information.
* Data warehouse thechnology is available to accumulate historical situation data from normal applications and dataases. These data then can be made available outside of the original applications through "Business Intelligence" (BI) tools. This works well for managemnt information and corporate governance but the inittial investment can be substantial and is less effective to support executive tasks and investigations.
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